Indigo is among the oldest dyes to be used for textile dyeing and printing. Many Asian countries, such as India Japan, and Southeast Asian nations have used indigo as a dye for centuries.

Indigo is an organic compound with a distinctive blue colour. Historically, indigo was natural dye extracted from the leaves of certain plants, and this process was important economically because blue dyes were once rare. A large percentage of indigo dye produced today, several thousand tonnes each year, is synthetic. The blue often associated with denim cloth and blue jeans.